ヴィエトナム北部山地の立地環境と傾斜地農業 : サパを事例として

概要

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Sloping land agriculture being condunted by ethnic minorities in Sa Pa district was studied from the viewpoint of soil snd water conservation. Sa Pa has an annual rainfall of about 2,800 mm with monthly temperature changing from 29℃ in July to -3℃ in December. Strongly weathered soils (Acrisols) are widely distributed in Sa Pa district. Paddy rice, maize, and vegetables are main crops. There are two types of cultivation of "terraced paddy fields" and "slash and burn farming" in the district. The terracing often has slopes with 25-30 degrees. Soil and nutrient losses from the sloping land are occurred by water erosion. Irrigation water is not sufficient in winter of the dry season, precluding the farming in this season. In slush and burn farming, cultivation is done for 3 years, but subsequent 4-10 years of fallow may not be enough fir recovery of vegetation. Slushu and burn in addition to fuel woodcutting made forest cover to decrease drastically until around 1990, but aforestation has been done recently by the government assistance. Altough there are still 4,000 ha of estimated arable lands,their slope and soil conditions are so unfavorable that selection of crops suitable to the land must be carried carefully in further cultivation.
九州大学の論文